power detecteur Power Supply: 8pcs 1.5V Batteries in Series Emitting Frequency: 6.99KHz Signal Frequency: 437KHz Indicators: Visual: Lever Meter Sound:2Speaker or Earphone (Earphone not included) Function: Disc: Ground Balanc; Distinguish Ferrous and Non-Ferrous Metal Controls: Critical Sound Tuner; Function Tuner Operating Current: 300mA MAX at MAX Volume The Detecting Depth (Max): 1.5-2 Meters Sensitivity:25-30cm for a US(25cent),